LDL cholesterol- Direct Enzymatic Method of Measurement

Low-density lipoproteins (LDL) are a type of lipoprotein that carries cholesterol to the peripheral tissues. LDL cholesterol is considered bad cholesterol. That means that the greater is the value of LDL, the greater will be the amount of cholesterol in the tissues. Similarly, an increase in the level of bad cholesterol can lead to different kinds of health problems such as heart diseases. You can measure it by direct enzymatic method, precipitation method, etc. Here we will discuss the direct enzymatic method of measurement of the LDL with a help of a semi-auto biochemistry analyzer.

Finally, we will discuss the contact details of an authorized dealer for you to purchase the reagent of Spinreact company in Kathmandu, Nepal.

LDL Cholesterol Range

The value shown below is the level of LDL cholesterol found in the bloodstream (serum). However, this is an approximate value. This value can slightly vary from one laboratory to another, based on the method of testing, the type of reagent used, etc. It can also differ due to geographical variation, habitat, age, sex, etc.

  • No treatment required < 150 mg/dl
  • Suspect range 150–190 mg/dl
  • Treatment required > 190 mg/dl

If the level of LDL cholesterol in the blood becomes abnormal, he/she should visit the doctor for further investigation.

How to Lower LDL Cholesterol Level?

Since it is bad cholesterol, you need to lower it down in the bloodstream. High cholesterol in the tissues can lead to heart diseases, obesity, diabetes, nephrosis, etc. Some of the ways to reduce the cholesterol level in the human body are as follows.

  • Do regular physical exercises. This will help you to reduce your excess body weight.
  • Reduce the consumption of unhealthy fat of meat, butter, cheese, etc. Avoid processed foods. Instead of that, consume unsaturated fats from vegetable oils, avocado, etc.
  • Avoid alcoholism because it never does you any good.
  • Avoid smoking or secondhand smoking.
  • Reduce the excess consumption of carbohydrates, sugar, etc from your diet.

Direct Enzymatic Method for LDL Cholesterol Measurement

1. Principle Reaction

The following method is a two-step method. In the first step, the reagent helps to remove all the non-LDL cholesterol from the serum. Then, in the second step, there will be a measurement of LDL cholesterol. This is possible with the help of cholesterol esterase (CHE),  cholesterol oxidase (CHOD), and peroxidase (POD). The final product will be the colored quinonimine dye.

The intensity of the dye is directly proportional to the concentration of LDL present in the serum.

2. Sample Preparation

The table, shown below for LDL cholesterol measurement is valid for colorimetric measurement of the reagents of  Tulip and Accurex Companies. So, if you have the reagent kit of any other company, then there can be minor fluctuation in the method.

Mix 5 μl of sample/calibrator with 375 μl of the first reagent. Then incubate the solution at 37°C for 5 mins. After that, add 125 μl of the second reagent to the solution. After incubating the solution for 5 more mins, feed the solution in a semi-auto biochemistry analyzer/ colorimeter.

For reagent blank (tulip), you do not need a sample in the above paragraph.  For accurex, you do not need to make a reagent blank.

Always remember that sipping volume < sample volume + reagent volume. So that means, make sufficient sample volume to feed into the semi-auto biochemistry analyzer. Else, it will suck up the air and will give the fault reading.

If the concentration of LDL cholesterol is too high (out of range/ non-linear), then dilute the sample with 0.9% NaCl or distilled water at the ratio of 1:y. Finally, when you get the result, multiply the value with the dilution factor (1+y).

3. Programming of LDL Cholesterol for a Semi-auto Biochemistry Analyzer (Direct Enzymatic Method)

LDL Cholesterol, Direct Enzymatic Method
Direct Enzymatic Method

4. Handling of LDL Cholesterol Reagent

You need to be extra careful while handling the reagents. So here are few tips that you are suggested to follow.

  • Wear an apron and surgical gloves before carrying out the measurement. Else the reagents may spoil your clothes. Hence the dress may get damaged.
  • Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
  • Once you open the reagent bottles, the lifespan will decrease. So, look in your reagent kit literature for that.
  • Bring the reagents and samples to room temperature before you can carry out any measurement.
  • Always store reagents in the refrigerator when not in use.

Supplier of LDL Cholesterol Reagent

Accurex, Tulip, Analyticon, Diasys, Erba, Human, etc are a few of the reagents used in Nepal. Among them, Spinreact is also one of the most widely used reagents throughout the country. If you want to purchase the reagent, then you can contact an authorized dealer of Spinreact known as Mandawi Enterprises Pvt. Ltd. You can contact the given number ((+977 9849034738). The supplier is located in Thapathali, Kathmandu.


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